This proposal is for a continuation of studies on the unusual bacteriophage, phi 6, of Pseudomonas phaseolicola. The phage is unique because it contains a lipid envelope and a tripartite segmented dsRNA genome. Current studies are focusing on (a) physical properties of the phage and the phage nucleocapsid, (b) characterization of the RNA product formed by the phage RNA polymerase, and (c) determining whether plasmid DNA in the host is correlated with resistance or susceptibility to the phage. BIBLIOGRAPHIC REFERENCES: Van Etten, J. L., L. Lane, C. Gonzalez, J. Partridge, and A. Vidaver. 1976. Comparative properties of bacteriophage phi 6 and phi 6 nucleocapsid. J. Virol. 18:652-658. Gonzalez, C. F., W. G. Langenberg, J. L. Van Etten, and A. K. Vidaver. 1977. Ultrastructure of bacteriophage phi 6: arrangement of the double-stranded RNA and envelope. J. Gen. Virol. (In press).